Data Transfer
11-22
ADSP-214xx SHARC Processor Hardware Reference
ping-pong DMA, initialize the corresponding
IDP_DMA_IxA
,
IDP_DMA_IxB
,
IDP_DMA_Mx
and
IDP_DMA_PCx
registers.
DMA transfers for all 8 channels can be interrupted by changing the
IDP_DMA_EN
bit in the
IDP_CTL0
register. None of the other control settings
(except for the
IDP_EN
bit) should be changed. Clearing the
IDP_DMA_EN
bit (= 0) does not affect the data in the FIFO, it only stops DMA transfers.
If the IDP remains enabled, an interrupted DMA can be resumed by
setting the
IDP_DMA_EN
bit again. But resetting the
IDP_EN
bit flushes the
data in the FIFO. If the bit is set again, the FIFO starts accepting new
data.
Programs can drop DMA requests from the FIFO if needed. If one chan-
nel has finished its DMA, and the global
IDP_DMA_EN
bit is still set (=1),
any data corresponding to that channel is ignored by the DMA machine.
This feature is provided to avoid stalling the DMA of other channels,
which are still in an active DMA state. To avoid data loss in the finished
channel, programs can clear (=0)
IDP_DMA_EN
bit as discussed in
previously.
Multichannel FIFO Status
The state of all eight DMA channels is reflected in the
IDP_DMAx_STAT
bits
(bits 24–17 of
DAI_STAT
register). These bits are set once the
IDP_DMA_EN
and
IDP_DMA_ENx
bits are set, and remain set until the last data from that
channel is transferred. Even if
IDP_DMA_EN
and
IDP_DMA_ENx
bits remain
set, the
IDP_DMAx_STAT
bits clear once the required number of data trans-
fers takes place.
Note that when a DMA channel is not used (that is, parameter reg-
isters are at their default values), the DMA channel’s corresponding
IDP_DMAx_STAT
bit is cleared (= 0).
If the combined data rate from the channels is more than the DMA can
service, a FIFO overflow occurs. This condition is reflected for each chan-
nel by the individual overflow bits (
SRU_OVFx
) in the
DAI_STAT0
register.
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Содержание SHARC ADSP-214 Series
Страница 60: ...Contents lx ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 72: ...Notation Conventions lxxii ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 130: ...Programming Model 2 52 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 264: ...Programming Models 3 134 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 290: ...Programming Model 4 26 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 296: ...Programming Model 5 6 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 396: ...Effect Latency 7 28 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 520: ...Programming Model 10 62 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 616: ...Debug Features 14 22 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 656: ...Programming Model 15 40 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 714: ...Programming Model 19 10 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 1132: ...Register Listing A 306 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 1192: ...Index I 34 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...